A trench gate IGBT is used as a transistor with low on-resistance, and as one form thereof, an IE type trench gate IGBT using an IE (Injection Enhancement) effect is known. The IE effect means that holes are made difficult to discharge from the emitter electrode side when the IGBT is in an ON state, whereby the concentration of charges stored in the drift region is increased to reduce the on-resistance.
In the IE type trench gate IGBT, for example, Japanese Patent Application Laid-Open No. 2012-256839 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2013-140885 (Patent Document 2) disclose that the active cell region connected to the emitter electrode and the inactive cell region including the floating region are alternately arranged in the cell-forming region. Patent Document 1 discloses a structure of the GG type (gate-gate type) where two trench gates arranged in order are coupled to the gate electrode in the active cell region. Patent Document 2 discloses a structure of the EGE type (emitter-gate-emitter type) where three trench gates arranged in order are coupled to the emitter electrode, the gate electrode, and the emitter electrode in this order, in the active cell region.